People have a fundamental need for positive and lasting relationships. In this article, we provide an overview of social psychological research on the topic of social acceptance and rejection. After defining these terms, we describe the need to belong and how it enabled early humans to fulfill their survival and reproductive goals. Next, we review research on the effects of social rejection on emotional, cognitive, behavioral, and biological responses. We also describe research on the neural correlates of social rejection. We offer a theoretical account to explain when and why social rejection produces desirable and undesirable outcomes. We then review evidence regarding how people cope with the pain of social rejection. We conclude by identifying factors associated with heightened and diminished responses to social rejection. © The Author(s) 2011.